Refactor and add last week released stories

* Add last week release stories
* Refactor stories helper methods
* Sort stories by story id
Show released last week stories under released
Fix and cache estimate calculation

* Cache estimate calculation per project
* Fix estimate calculation when including stories accepted last week but not yet released
Reduce stories caching to 12 hours
Add my stories and last week filters

* Add a chechbox to toggle displaying only current user's stories
* Add a checkbox to toggle showing last week's released stories
* Sort stories by project and id to keep consistent order
Reuse updated_at parameter for presenter caching
Merge pull request #3 from dulyanov/show_last_week_released

Show stories released last week